Load distribution indicator



Sept. 16, J. A. LOAD DISTRIBU-TION INDICATOR Filed Oct. 8, 1937 3 Sheets-Sheet l FVG. 2.

/NA/ NTO/Q l ,4. POCHE.

Sept. 16, 1941. J. A. ROCH LOAD DISTRIBUTION INDICATOR Filed Oct. 8, 1937 3 Sheets-Sheet 2 5. ma. F

la J M J. A. ROCH LOAD DISTRIBUTON INDICATOR Sept. 16, 1 941.

5 Sheets-Sheet 3 Filed Oct. 8, 1937 Q M E F/G /O,

Patented Sept. 16, 1941' UNITED 'STATES Pmeml OFFICE 1.01m` Amirra:i'iztlis'rs'ngtemplearon Jean A. me, Di'yton, Ollio Y Application 5,1957. semi No, 168,027 1a-ionen. (ci. zes- 40) (Gmini mer-athena orma s, Issa, mucca Aprile., im; 37o o. G. 757) The invention described herein maybe'manufactured and used by orfor the Government for governmental purposes, without the payment to me of any royalty thereon.

The present invention, which relates in general to vehicles and more particularlyA to means for indicating improper load--distributiontheres-- within prior to operation thereof, is a .continuaq tion, in part, of my co-pending application, Serial No. 710,475, nled February 9, 1934.

The primary object of the invention is to provide means whereby operators of land or air vehicles may be acquainted in advance of load place; ments introducing unnecessary hazard to the normal operation of their vehicles.

My invention finds particular application to aircraft in that it provides means whereby the pilot mayreadily ascertain that lthe cargo or passenger load he is transporting' is disposed in a manner bringing the center of gravity of the whole Within the designed longitudinal and lat-l eral limits of his aircraft.

Another 4object of the invention is to provide .in aircraft equipped with outboard fuel tanks,

means by which the pilot may detect improper filling of fuel tanks prior to take-off.

With the foregoing and other objects in view, which will appear as the description proceeds, the invention consists of certain new and novel improvements in load distribution indicators which will be hereinafter more fully illustrated and described in the accompanying drawings and more particularly pointed out in the appended claims.

Referring to the drawings, in which numerals of like character designate similar parts throughout the several views:

Fig. 1 shows a diagrammatic installation of my invention;

Fig. 2 shows the indicating element of a preferred embodiment of my invention;

Fig. 3 is a cross-sectional view ofx Fig. 2 on' the line 3 3;

Fig. 4 is a partial cross-sectional view "of Fig. 3 on the line 4 4;

Fig. 5 is a second embodimentofthel indicating element;

Fig. lis a cross-sectional viewof Fig. 5 on the line 6;-5;

Fig; 7 shows a third embodiment of the indicating; element;

Fig'. a i

interconnection o! the-indicating elementi-im. 1 with three struts-supporting .55

:cross-sectional view of Fig. 7 on the indicating element 9 is the tail and landing gear wheels of an airplane;

and

Fig. -10 is a partial cross-sectional view of Fig. 4 on the line N Ill.

In Figs. land 9, the central portion of a wing panel l is shown fixedly secured to a. fuselage 2 of a conventional airplane. Landing gear wheels I, carried by independent axles 69, are yieldingly connected to the undersurface of the Wing panel l by means of oil'and air struts 5 and 6, mounting lugs 10, bolts 1l, retaining nuts 'l2 and lock washers 13. A tail wheel 8, carried by a conventional yoke 14, is yieldingly connected to the fuselage 2 just forward of tail surfaces 3 by means of an oil and air strut 1, a mounting lug 15 depending from a fuselage brace member 16, bolts 'I1 and 18, retaining nuts 'i9 and lock washers l0. Conventional longitudinal and lateral axes :lz-z and y-y are shown passing through the CG of Athe aforesaid airplane. Within convenient vision of the pilot is located an indicating element 9 of my invention. The operatively connected to an upper extremity of each of the aforesaid struts, a tube I0a terminating at the right strut 5, a tube Ic terminating at the left strut 6, and a tube lub terminating at the rear strut l. In accordance with my invention, a change in indication of the element 9 will take place only when the relation of the load ratios at the struts 5, 6 and I change. Referring to Fig. 1 and assuming W to represent the gross weight of an airplane loaded inl any manner, this weight may be broken down into Wr supported by strut 1, Wa supported by strut 5, and WL supported by strut 6. If the indication of the element 9 is to remain unchanged, it is essential that each of the ratios W'r/ (Wn-l-Wr.) Wa/ (WL-'l-WT) and WL/(Wn-l-W'r) in and of itself remain constant. It is thus evident that mere increase or decrease in the magnitude of W, i. e., the sum of the reactions, will not cause the element 9 to change its indication. On the other hand, any shifting of "W parallel to axis :r-:c or axis y-y will destroy the constancy of all of the above ratios and cause the element 9 to change indication.

Fig. 2 shows the face of one embodiment of the indicating elementl 9. A cover glass Il is secured to the body portion of the indicating element 9 by means of a retaining ring I2 and screws I3. The cover glass il is provided with a phantom outline I4 depicting the forward plan view of a conventional airplane. 'I'he longitudinal center line of the outline I4 is indicated by a reference line 'Il corresponding to longitudinal axis l eiected by placing the airplane on scales and the computed center of gravity location then inscribed upon the dial, by passing of a reference line I9 corresponding to lateral axis y-y' of Fig. 1 through the midpoint of the plan projection of the indicating knob I8 normal to reference line I5. 'I'he point of intersection of reference lines I and I9 represents longitudinal and lateral placements of center of Vgravity of an aircraft to which my invention is applied. Additional reference lines 2l and2l are positioned fore and aft of the reference line I9 and parallel thereto. The full signicance of the longitudinal reference lines I6 and I1 and the lateral reference lines 2l and 2l will be dealt with hereinafter.

Fig. 3 is a longitudinal cross-sectional view of the indicating element 'shownin Fig. 2. The body portion thereof consists of a shell or housing 22, hanged at its uppermost portion to support the glass II and retaining ring I2. The lower central portion of the housing 221s provided with a tapped boss 23 into which is screwed Ya needle 24. A check nut 25 is provided for locking the needle 24 against rotationalmovement with respect to the housing 22. The needle 24 is reduced in cross-sectional area immediately above the check'ynut 25 to lend flexibility thereto. 'I'he central portion of the needle 24 is enlarged to form a triangular prism 26. The needle 24 terminates at its upper extremity in the indicating knob I8, previously shown in Fig.. 2, the said upper extremity being reduced in diameter to receive and hold a disc 21. A plate 28 is cut away at its central portion, to permit passage of the indicating knob I3 therethrough. The underside of the plate 28 rests upon brackets 29 ilxedly secured to the inner side of the housing 22. An end prole of a Sylphon 30h i is shown immediately behind the prism 26.

Fig. 4 shows a cross-sectional view, in plan, of the indicating element 8 taken from a point immediately above the Sylphon 36h of Fig. 3. The bases of the Sylphons 38a,- 36b and 38e are xedly attached to the housing 22 and extend therethrough to form threaded bosses 3I, adapted to receive nuts 32, of the tubes Illa, IIIb and Ic. The outer extremities of the Sylphons 39a, 36h

and 3llcv are provided with internal bosses, into which are screwed adjustable stems 33. The extremities of the stems 33 are curvedly shaped and are provided with holes 34 for receiving a tool for rotating the stems about their longitudinal axes. the stems 33 are locked against rotation with respect to the Sylphons 33a, 36b'and 3Ilcby means of checkA nuts 35. It-should be noted that the Sylphon 36a is connected with the tube Ita, the Sylphon 3817 with the tube I8b' and the Sylphon 36e with the tube I le;v thereby operatively con- Following the aforesaid adjustment,

pressure maintained in the rear strut 1 to insure desired indication change in the element 9. The- Sylphons 30a, 30h, and '300, the Bourdon tubes 36a, 36h and 36o (discussed below), or other gauge element serving a similar purpose can be selected so that they will have characteristics giving desired calibrations on cover glass II.

The three stems 33 are so adjusted with reference to the Sylphons 30a, 30h and 30e that the indicating knob I8 is made to assume the position shown in Fig. 2. It is to be understood that slight longitudinal variation of the indicating knob I8, with reference to the transverse line I9, may be arbitrarily assumed to eiect allowance for unavoidable differences arising due to unusual shifting of the center of gravity between the extremes of weight empty and fully loaded condition. In this connection it should'be stated that less discrepancy is met with in cargo airplanes than in passenger carrying transports. In the latter type of airplane, it is possible for a diminished passenger load to be so positioned at the aft extremity of the passenger cabin that the longitudinal balance of the aircraft is seriously affected. Through employment of my invention, it is possible for the pilot to detect the aforementioned improper passenger distribution, prior to take-off, and to effect proper redistribution of the passenger load.

Not desiring to limit myself, in indicating pressure dierences between struts 5, 6, and 1, to exclusive use of Sylphon indicating means, I have shown in Figs. 5 and 6 a second embodiment of indicating element 9. Three Bourdon tubes 36a, 36h and 36o, are xedly secured at their outer extremities to base brackets 31. The brackets 31 are in turn iixedly secured to the bottom of a housing 38 and extend through the underside thereof to form threaded bosses 3l. 'Ihe outer end of each Bourdon tube is operatively connected to a tube by means of a nut 32. A mounting base 39 is centrally disposed within the housing 38. A T-shaped connector 40 is slidably secured to the base 39 by means of four rollers 4I and retaining pins 42. The connector 40 is provided with a rack portion 43 held in operable engagement with a pinion gear 44. The lower extremity of the gear 44 is journaled to the base 39, while the upper extremity thereof is similarly Journaled in a bearing provided at the central portion of a plate 45.` 'Ihe plate 45 is inserted into the open end of the housing 38 and pressed down until it rests securely against the three brackets 31. A pointer 46 is rmly secured to the upper extremity of the gear 44. The inner extremities of the Bourdon tubes 36a and 36a are pivotally secured to the lower extremities of the connector 40 by means of pins 41, while the inner necting, in order named, the Sylphons 30a, 38h

and 36e with struts 5, 1, and 6, respectively. It should be further noted at this point that the operating pressures'of the'forward'struts 5 and 6 extremity of Bourdon tube 36h is similarly attached to the upper extremity of the connector 49 by means of a pin 41. The upper portion of the housing 38 is anged outwardly in order that the open endthereof may be sealed by a cover glass 48 and retaining ring 49. The ring 49 is secured to the aforementioned anged portion of.

the housing 38 bymeans of screws 50. It will be noted that the plate 45 is provided with two legends 5I and 52. When the outer extremity of the pointer 46 is centrally disposed with reference to legend 5I, as shown in Fig. 5, a condition of maximum tail heaviness is indicated. When the outer extremity ofthe pointer 46 is centrally disposedwith reference tolegend 52,..a condition of maximum nose heaviness exists.

asoman Figs. 7 and 8 show modification, in part, of certain of the elements of Figs. and 6. The inner extremities of the Bourdon tubes 35a and c are provided with linked connection to a modified connector. A portion of the link connection extends through an opening 53 provided in the plate 45, and takes the form of pointers 54 and 55. Detailed operation of the pointers 54 and 55, as well as significance of the legends 55 through 5l, are dealt with below.

u Fig. 8 is a cross-sectional view through they line 5-5 of Fig. '1, and discloses linked attachment of a connector 52 to Bourdon tubes 35a and 35e respectively. It will be noted that the T- shaped connector 4l utilized in Figs. 5 and 6, has been replaced by a simple link with identical ends. The pointers 54 and 55 are concentrically and pivotally attached to the lower extremity of the connector 52 by means of the pin 43, of the pointer 54 and the boss 54, of the pointer 55. It will be noted that links 55 and 55 form an operative connection between the inner extremities of the Bourdon tubes 56a and 35e and the lower extremity of the connector 62. The pin 53 serves to secure the inner extremities of the links 55 and ss to the connector s2, while the pms s1 and ss of the pointers 54 and 55, respectively, serve to further link the aforementioned connector to the inner extremities of the Bourdon tubes 55a and 36e. The operation of the aforementioned parts are described in detail below.

Adjustment of the iirst embodiment of my indicating element s may best' be understood by reference to Figs. 3 and 4. The glass Il, the retaining ring i2 and the plate 25 are removed from the housing 22, the check nuts 35 loosened, and the curved portions of the stems '33 so adjusted with respect to one another that the center of the indicating knob I8 is brought into coincidence with the longitudinal axis of the housing 22. Upon reinstallation of the plate 2l, re' taining ring l2, and glass I I, the plan appearance of the indicating knob Il will be that of Fig. 2. The aforementioned adiustment may be readily accomplished by insertion oi' the proper tool within the openings I4 provided at the outer extremities of the stems ll. Following desired adjustment the stems 33 are locked fast to their respective Sylphons by means of the check nuts 35.

Let it be assumed that an airplane is serviced in preparation for take-off. Let it be further assumed that only a partial capacity load is avaiiable for transportation and that this load is improperly concentrated at the rear of the load carrying compartment. The aforementioned load placement will cause the center oi' gravity of the airplane to move to the rear of the designed position of the center of gravity of the airplane with load properly disposed. This rearward shifting of the load will bring about pressure decrease ln the struts 5 and 5 and pressure increase in the strut 1. Pressure changes within the struts 5, 5 and l are in turn transmitted through the tubes ma, mc and nb to the sylphons sla, nc and alb,- 1

causing the two former to recede andthe latter to move outwardly from the supporting wall of the housing 21. vAs viewed in Fig. 4, downward movement of the triangular prism 2G will cause corresponding .downward movement of the indicating knob I5 towards the line 2l shown in Fig. 2. Through reference to the -indicating element 9 the pilot is advised of the presence or absence of dangerous cargo placementland if th-.I

former prevails may take steps to correct the same prior to take-olf.

Where multi-engined airplanes are equipped with my invention and passengers or cargo are carried outboard of the fuselage, improper lat-` eral disposition of the aforementioned load may be readily ascertained by reference to the indieating element 9. Assuming unduev shifting of the load to the right of the longitudinal axis x-x of the fuselage 2, shown in Fig. l, pressure increase in the strut 5 and pressure decrease in the strut 5 will occur. As a result of the foregoing pressure diflerencea'the Sylphon 35a will expand outwardly and the Sylphon 10c contract inwardly, causing corresponding right-hand movement of the indicating knob I8 towards the line I5 shown in Fig. 2. It will be noted that no pressure change occurs in the strut 1. Through reference to the indicating element 9, the pilot readily detects necessity for load rearrangement. The operation of the second embodiment of the indicating element 9 is set forth below. Referring to Figs. 5 and 6, it will be seen that abnormal pressure increase in the strut l causes expansion of the Bourdon tube 36o with accompanying downward movement of the connector 40. Simultaneous 4downward movement of the rack portion 43 causes counter-clockwise movement of the pinion gear 44 and pointer 45 fixedly secured thereto. The aforementioned movement causes the pointer 45 to take the position shown in Fig. 5 with the tip portion thereof opposite the legend Tail heavy." i It will be noted in the preceding embodiment of my indicating element 5 that the inner extremities of the Bourdon tubes 38a and 35e are fixed against longitudinal movement with respect to the connector 45. In the third embodiment of my indicating element 9, a linkage is introduced permitting independent movement of the inner end of Bourdon tube 36a with respect to the inner end of the Bourdon tube 5Go. In Figs. 'I and 8, it will be seen that while the bases of the pointers 54 and 55 are pivoted about a common pin 53, the body portions of the aforementioned pointers have independent linked connection through the pins 61 and 68 and auxiliary links 55 and 56 with the outer extremities of the Bourdon tubes 38a and 36o. Assuming, in a multi-engined airplane, undue shifting of load to the right of the longitudinal axis of the fuselage 2 with attendant pressure increase in the strut 5 and pressure decrease in the strut 6, the Bourdon tube 55a operatively connected with the strut 5 will expand, causing counter-clockwise rotation of the pointer 55 towards the legend Heavy and the Bourdon tube 36e operatively connected with the strut 5, will contract, causing counter-clockwise rotation of the'pointer 54 towards the legend Light Obviously, shifting of Ythe aforementioned load to the left of vthe longitudinal axis .r-f-z of the fuselage 2 brings about reversal of Pointer readings, either set of which are readily understandable to a. pilot referring to the same. Itis also'apparent that proper lateral distribution of the passengers or cargo of an airplane, when combined with improper longitudinal disposition of the same, effects consistent relationship between the readings o f the pointer 45 and those-of the correlated pointers 54- and 55. Exce'ssive forward placement of a load isattended by upward tilt of the pointers 54 and 55 towards thelegend ,Heavy and movement of the-fpointer 45 to a position opposite the legend Nose heavy."-

Rearward placementof a. load is accomplished ,counter-clockwise movement of the pointer 48 81s composed of a cylinder 8l and a hollow pistn 02. The cylinder 8| vis sealed at its bottom extremity by va combination mounting lug-header 0.3. A metering pin 84, provided with a bulletshaped or stream-lined head 85 and a calculated or predetermined frustro-conically tapered body portion 86, is secured fast to the mounting 4lugheader 83. The upper end of the chamber 8| is ilared out to provide a sealing gland 81. The gland 81 is composed of a packing 88, a retaining ring 89, and a packing gland nut 90. The piston 82 is provided with a head 9|, having oil grooves 92 and a central orifice 93, and with a central hollow chamber 94. The upper extremity of the piston 82 is secured to the mounting lug 10 of the wing panel by means of a combination mounting lug-header 95. Immediately below the aforesaid connection are provided a mounting boss 96 for a pipe connection 91 and a fluid filler tube 98 threaded at its upper end to receive ,an air-or-oil ingress fitting 99, the detailed functions of which will be more fully stated hereinafter. The outboard end of the pipe |a is connected. to the piston 82 of the strut 5by means of the fitting 91. The remaining tubings |0b and |0c, leading away from the centrally disposed indicating element 9, are similarly connected to struts 6 and 1 by means of two like pipe fittings 91.

The three struts shown in Fig. 9 represent, respectively, the right landing gear wheel strut 5, left landing gear wheel strut 6, and the tail wheel strut 1, of an airplane. The figure also shows the connection of the center of gravity indicator instrument 9 to air chamber portions |00 of the hollow pistons 82 by means of pipes |0a, |0b, and |00.

In current airplanes,4 it is customary to service air and oil struts without jacking up the airplane, i. e., the bottom of the piston head 9| rests upon and is entirely supported by the top face of mounting lug-header 83. The proper quantity of oil is poured in through tube 98, which, by the length of its depending portion, governs the quantity introduced, since it would be impossible to add more oil after the level reaches the bottom opening of this tube, the upper chamber being sealed. Fitting 99, which incorporates an air valve |0|, is then installed and the air ifnilation process is begun by means of a suitable high pressureair pump. At first, there is no relative displacement between the cylinder 8| and the piston l2, but when: a pressure sunlcient to equilibrate the forces which hold the aforesaid cylinder and piston in the collapsed condition is reached, further pumping of air into the chamber .|00 does not increase the pressure therewithin but only serves to extend the over-all length -'of the strut 5, forcing theliquid |02 through the orifice 93 so that the volume of the lower chamber |03 increases from zero to the value shown in Fig. 9r corresponding to the spacing h1 between cylinder bottom 8| and lower piston face 82, which is the same volume as that corresponding to the space hz in the upper cham- The air pressure above the liquid |02 is,

ber. therefore, constant, even-if pumping should be abnormally continued until the strut had been fully extended, after which the pressure therewithin would begin to increase, if the, pumping process were continued. In current; practice,

however, this pumping process is continued only until the shock absorber strut isextended about per cent of its maximum possible travel, corl responding to a normal static position in which is positioned within the central orifice 93. During the initial impact of landing, metering of liquid through the orifice 98 is so restricted by the head that the pneumatic suspension'medium represented by the air in any one of the tires 4 will be compressed and said tire deflected to a predetermined extent. During this period of ldeflection of the aforesaid tire, the impact load of the airplane will have been built up to an allowable maximum and, in addition, a part of the kinetic energy of the airplane will have been absorbed by metering of liquid through the restricted orice 83 and the head 85 will have moved slightly beyond the orifice 93. Thereafter, the aforesaid tire remains deected under said maximum impact load as the remainder of the kinetic energy is being dissipated. The dimensions of the tapered body portion 86 (of themetering pin 84) are so calculated as to maintain the aforesaid predetermined load substantially constant throughout the maior portion of the downward stroke of the hollow piston 82. Upon termination of the latter, the liquid from the lower chamber |03 has been transferred into the upper chamber 94, thus compressing the air ktrapped in the latter chamber back to the normal inflation pressure or slightly beyond if the landing is so severe as to cause the bottom surface of the piston head 9| to come into contact with the top surface oi the mounting lug-header 8?, If this extreme condition occurs, the pressure in the air chamber |00, above liquid |02, will be increased by some 30 per cent, the volume of the air chamber |00 being selected beforehand to prevent a much higher pressure from being generated. It will thus be seen that the instrument connected with the three air chambers |00 will never be greatly overloaded, whereas the liquid pressure in the lower chamber |02 may reach very high values due to thegreat speed at which the shock strut may be compressed.y It thus follows that while the airplane may auer acceleratlons of high magnitude, such asfour to seven times gravity, and the oil in the lower chamber |03 may suffer pressures correspondingly greater than the normal inflation pressure during the impact with the ground, the pressure in the air chamber 00 will sull'er only a fractional increment above its value when the airplane is at rest on the ground, and consequently no destruction of.: the -instrument 9 can result under any operating condition of the shock absorber.

In Fig." 10, I have provided the needle 24 with auxiliary means for manually adjusting the indicating knob I8 along the longitudinal reference line I5 of Fig'. 2. The aforesaid adjustment consists of a J-shaped spring |04, with a centrally located upper slot |05, fixed to the needle 24 by means of a rivet |06. The spring |04 is inFig. 4. 'I'he same scheme of adjustment may be applied to `both Figs. and 7. In the former, the spring |09 is shown iixed to the bottom of the connector 40 by means oi a screw I |0.

II claim:

1. In an indicating system, the combination with three shock struts, each strut having a plurality of chambers, one of said chambers being subject to a pressure less than that of another during the shock of landing, of means for indicating the pressure ratio relation offthe lesser pressure chambers of said shock struts comprising,'a corresponding number of separate pressure responsive elements operatively connected with said lesser pressure chambers. and an indicator operatively connected with said pressure responsive elements capable of movement in at least two different planes as a function of a change in the pressure ratio relation of said lesser pressure chambers.

2. In an indicating system, the combination with three shock struts, each strut having a plurality of chambers, one of said chambers being subject to a pressure less than that or another during the shock of landing, of means for indicating the pressure ratio A.relation of the lesser pressure chambers of said shock'struts comprising, separatepressure responsive means comconnecting the nxed end of one or said pressure responsive elements to one oi' said pressure sources,a connector having a rack and being sildabLv secured to said housing as well as pivotally attached to the free ends of said pressure responsive elements, a pinion gear pivotally secured to said housing in operable en-l gagement with said connector rack, and a pointer attached to said gear for indicating degree of rotation of same.

7. A longitudinal load distribution indicator comprising, a plurality of pressure responsive elements disposed in a common plane and adapted to be connected to a like number of independent pressure sources, a housing for supporting a iixed end of each pressure responsive element, a plurality oi tubes, each ot said tubes operative- '1y connecting the fixed end -of one of said pressure responsive elements to one of said pressure sources, a connector having -a rack and being' slidably secured to said housing aswell as pivotally attached to the free ends o! said pressure responsive elements, a pinion gear pivotaliy secured to said housing in operable engagement g5 with said connector rack, a pointer nxedly'atmunicatively connected with said lesser pressure chambers and an indicator operatively connected with said pressurev responsive elements capable of movement in at least two different planes as a function o! a change in the pressure ratio relation of said lesser pressure chambers.

different planes coupled to said pressure responsive elements in such a manner as to indicate any variation in the pressure ratio relation of said pressure sources.

5. An indicator comprising, three pressure responsive elements adapted to be connected to three independent pressure sources and indicating means capable of movement in at least two different planes coupled to said pressure responsive elements in such a manner as to indicate any variation in the pressure ratio relation oi said pressure sources, and adiusting means for setting said indicator means to a pre-determined position corresponding to a desired` pressure yratio relation. ,l

6. A longitudinal load Vdistribution indicator comprising, a plurality ofl pressure responsive elements .disposed 'in acommon plane' and adaptedto be connectedto a like number'of independent pressure sources,l a housing for supporting a iixed end of each pressure responsive element, a pluf tubes, each oi' said -tubes operatively 'lio tached to said gear and a scale associated with said pointer for interpreting movements thereof.

8. A longitudinal and lateral load distribution indicator comprising, a plurality of pressure responsive elements disposed in a common plane and, adapted to be connected to a like number of independent pressure sources. a housing for supporting a fixed end of each pressure responsive element, a plurality of tubes, each' of said tubes operatively connecting the fixed end of one oi said pressure responsive elements to one of said pressure sources, a connector having a rack and being slidably secured to said hous-A ing, one end oi said connector being pivotally attached to the free end of one of said pressure responsive elements, a pinion gear pivotally secured to said housing in operable engagement with said connector rack, a pointer ilxedly attached to said gear, a scale associated with said pointer for interpreting movements of said connector, and indicating means associated with the remaining end of said connector and movably independent and with the free ends of the remainder of said pressure responsive elements for showing relative movements between said connector and the aforesaid free ends of said lastmentioned responsive elements.

9. A load distribution indicator comprising, a plurality of pressure responsive elements disposed in a common plane and adapted to be connected to a like number of independent pressure sources, a housing for supporting a xed end 4 of each pressure responsive element, a plurality of tubes, each oi said tubes operatively connecting the xed end of one of said pressure responsive elements to one of said pressure sources, a connector having a rack and being slidably secured to said housing, one end of lsaid connector being pivotally attached to the free end of one of said pressure responsive elements, a pinion gear pivotally secured to said housing in operableengagement with said connector rack, a.` pointer ixedly attached to said gear, a scale associated with said pointer for ,interpreting movements thereof, and linkage means operatively connecting the remaining end of said connector to the free ends of the remaining pressure responsive elements, two elements of said linkage means forming pointers for indicating relative movements between said connector and the capable of transmitting both tension and compressive forces upon said indicating means to ob-` tain a double-acting effect from each of said elements so that said indicating means is operatively responsive to the combined eiects of all of said pressure-responsive elements for indicating relative load distribution with respect to each, of. said devices.

JEAN A. RocH. 

